Combinatorial weighing system

ABSTRACT

A combinatorial weighing system, wherein swing plate 9 disposed substantially in the middle of the interior of a feed hopper 1 uniformly distributes objects of weighing, particularly those liable to tangle each other, in the bottom of the feed hopper without causing localized gathering of the objects, and the objects are then transferred to conveyors 5 disposed close to each other at one of their respective ends and extending in mutually opposite directions until the other ends thereof are positioned outwardly of the lateral walls of the feed hopper, whereby the objects are fed, in amounts within an allowable range of weighing, to the associated automatic weighing machines.

The present invention relates to a combinatorial weighing system forweighing objects which are liable to tangle each other, andparticularly, agricultural products which are liable to tangle eachother, hardly slippery, and highly elastic, such as immature green peas.

Generally, in mass weighing and corrective weighing, what is regarded asof utmost importance to increase accuracy of weighing is orderlyarrangement of objects and uniformity of the density of flow of objectsin a constant quantity take-out device which feeds a weighing hopperwith objects of weighing. This is because the weight of objects whichare put in for correction after the first stage weighing determinesaccuracy of weighing. In a conventional weighing machine, in the case ofobjects whose shape is not fit for orderly arrangement and which differin size and weight from each other, it has been difficult to take outobjects in constant amounts during corrective weighing, with littlepossibility of obtaining high accuracy. The present applicant hasalready proposed a combinatorial weighing system which enables theweighing of such objects with high accuracy. If this combinatorialweighing system is composed of ten automatic weighing machines, theamount of objects which can be fed to each automatic weighing machine bythe constant quantity take-out device is 1/3-1/7 of the targetcombination weight; this allowable range of value, as compared with thatfor the conventional weighing system, is very wide. Even if thesecombinatorial weighing systems are used, however, it is difficult tocombinatorially weigh with high accuracy a particular agriculturalproduct which is liable to tangle each other, hardly slippery, andhighly elastic, such as immature green peas (such agricultural productbeing hereinafter referred to as immature green peas). This is because,with the conventional constant quantity take-out device using anelectromagnetic feeder, even if time control and amplitude control areeffected, immature green peas absorb vibration, so that it is difficultto take out immature green peas in constant amounts without deviatingfrom said weight range and feed them to individual automatic weighingmachines.

The present invention is intended to solve the above described problemencountered when immature green peas must be fed in constant amounts tothe automatic weighing machines of the combinatorial weighing system.

To this end, the invention provides a combinatorial weighing system,comprising a plurality of weighing mechanisms each comprising a feedhopper, a swing plate installed substantially in the middle of saidhopper and adapted to swing in a vertical plane, opposed conveyorsdispposed with their adjoining ends positioned below substantially themiddle of the bottom of the feed hopper and with their delivery endspositioned outwardly of the lower ends of the lateral walls of said feedhopper, and automatic weighing machines opposed to each other andpositioned below the delivery ends of the conveyors, whereincombinations of the weight values of objects weighed by the automaticweighing machines included in the individual weighing mechanisms arecomputed to provide a combination of weight values which is equal or thenearest to a predetermined weight.

According to the invention, objects of weighing are distributed in thebottom of the feed hopper with a uniform density without localizedgathering by the vertical swing movement of the swing plate, and thentaken out of the feed hopper within an allowable weight range by eachconveyor into the associated automatic weighing machine. Thus, objectsof weighing which are liable to tangle each other, hardly slippery, andhighly elastic, such as immature green peas, can be combinatoriallyweighed continuously and with high accuracy.

According to an embodiment of the invention, a combinatorial weighingsystem composed of a number of weighing machines arranged in two opposedrows comprises weighing mechanisms each comprising a swing plate whichis attached substantially centrally to the lateral walls of a feedhopper associated with opposed automatic weighing machines and which isadapted to vertically swing through about 45° on each side of thehorizontal for a predetermined time, and opposed conveyors which aredisposed with their adjoining ends positioned below substantially themiddle of the bottom of the feed hopper and with their delivery endspositioned outwardly of the lower ends of the lateral walls of the feedhopper and which are adapted to travel at a constant speed in mutuallyopposite directions for a predetermined time and provided on theirtransport surfaces with guide projections for guiding objects ofweighing, wherein in response to discharge signals from the weighinghoppers of automatic weighing machines selected as a result ofcomputations of combinations of weights, the vertical swing movement ofthe swing plate and the traveling movement of the conveyors aresuccessively effected to feed objects to the weighing hoppers for theselected weighing machines.

Thus, a particular agricultural product which is hardly slippery, liableto tangle each other, and highly elastic, such as immature green peas,in the feed hopper can be distributed in the bottom of the feed hopperwith uniform density without localized gathering, in such a manner thaton the side where the swing plate lowers, the objects are somewhat urgedagainst the transfer surface of the conveyor by being pressed down bythe swing plate, and on the side where the latter rises, the entangledobjects are separated by the swing plate. Since this distributed stateis established by effecting the vertical swing movement of the swingplate for a predetermined time subsequent to the sending of a dischargesignal from a weighing hopper, greater uniformity can be achieved.Further, unlike the conventional constant delivery device, since theurging force of the swing plate will never be directed toward thelateral walls of the feed hopper, there is no possibility of pressingobjects of weighing against the lateral walls of the feed hopper;therefore, there is no possibility of objects being damaged by theoutlet gate as they would otherwise gather into a mass during transfer;nor is there a possibility of their tangling each other after they haveleft the outlet gate. Further, uniformly distributed objects are placedon the conveyors, and after they have been arranged in predeterminedorderliness by the outlet gates of predetermined cross-section whilebeing prevented from slipping by the guide projections, they aretransferred to pool hoppers or directly to weighing hoppers, suchtransfer being effected for a predetermined time subsequent to dischargesignals from the weighing hoppers. Thus, it is possible to transferconstant amounts of objects to the weighing hoppers. As a result,objects of weighing can be taken out, in constant amounts, of the feedhoppers and fed, within an allowable weighing range, to the automaticweighing machines of the combinatorial weighing system. The use of theconstant quantity take-out device of the invention enables theweight-combinatorial weighing of a particular agricultural product whichis hardly slippery, liable to tangle each other, and highly elastic,such as immature green peas, in a continuous manner.

These and other objects and features of the invention will become moreapparent from the following description when read with reference to theaccompanying drawing.

The drawing schematically shows by way of example a combinatorialweighing system embodying the present invention.

Referring to the drawing, 1 denotes a feed hopper; 2 denotes a feedconveyor for immature green peas, disposed with its delivery endpositioned above the upper open end of the feed hopper 1; and 3 denoteslevel control phototubes attached to the upper portions of the lateralwalls of the feed hopper 1 and adapted to control the movement of thefeed conveyor 2 to thereby keep constant the amount of immature greenpeas fed to the hopper 1. Outlet gates 4 made of or coated withlow-friction Teflon are installed in opposed relation to transferconveyors 5 so that the area of openings defined therebetween may beadjusted. The transfer conveyors 5 are disposed with their adjoiningends positioned below substantially in the middle of the bottom of thefeed hopper 1 and with their delivery ends positioned outwardly of theoutlet gates 4, the transfer conveyors being driven in mutually oppositedirections for a predetermined time. The transfer conveyors may, forexample, be chain conveyors. Guide projections 6 for immature green peasare fixed on the conveyors 4 at regular intervals. The numeral 7 denotesa plate positioned over the adjoining ends of the conveyors 5 to preventfalling of immature green peas; 8 denotes a pivot shaft attachedsubstantially to the middle portions of the lateral walls of the feedhopper 1; and 9 denotes a swing plate pivotally mounted on the pivotshaft. The swing plate 9 is adapted to swing through about 45° on eachside of the horizontal for a predetermined time and mounted in such amanner that the raised position of the end of the swing plate is belowthe level determined by the level control phototubes 3 and the loweredposition thereof is spaced apart from the transfer surfaces of theconveyors 5 to provide a predetermined spacing therebetween. Poolhoppers 10 are opposed to each other and positioned below the deliveryends of the conveyors disposed outwardly of the outlet gates 4, the poolhoppers serving to temporarily store immature green peas in amountsequal to 1/3- 1/7 of the target weight. Automatic weighing machines 11adapted to receive immature green peas from the pool hoppers 10 andweigh them in cooperation with weighing hoppers 12.

The above described arrangement forms one unit of weighing mechanism,and five such units are arranged in series along a line perpendicular tothe plane of the drawing to form a combinatorial weighing system(comprising ten automatic weighing machines). The numeral 13 denotes acollecting chute for collecting immature green peas discharged from theautomatic weighing machines of the combinatorial weighing system; 14denotes a collecting hopper disposed at the bottom of the collectingchute; 15 denotes a belt conveyor; and 16 denotes a collecting box forimmature green peas placed on the belt conveyor.

The swing movement of the swing plate 9, the traveling movement of theconveyors 5, and the opening and closing movement of the lids of thepool hoppers are controlled by discharge signals from the weighinghoppers of the weighing mechanism belonging to each unit, i.e.,discharge signals from the weighing hoppers of automatic weighingmachines corresponding to a selected one of combinations of weightsmeasured by the automatic weighing machines of the combinatorialweighing system, these combinations being computed in an arithmeticcircuit. As for the swing plate 9, however, it is swung for apredetermined time set by a timer so that it will not agitate immaturegreen peas to an excessive extent. On the other hand, the opening andclosing movement of the lid of the collecting hopper 14 is effected inresponse to a signal indicating the arrival of the collecting box 16 ata position below the collecting hopper 14.

The operation of the weighing system constructed in the manner describedabove will now be described. First, immature green peas, which areobjects of weighing, are fed to the feed hopper 1 by the feedconveyor 1. This feeding of immature green peas is effected in such amanner as to maintain the level controlled by the level controlphototubes 3. Subsequently, the swing plate 9 is caused to swing throughabout 45° on each side of the horizon. The swing plate 9 operates suchthat on the side where it is lowered it lightly presses immature greenpeas against the transfer surface of the conveyor 5 without pressingthem against the lateral walls of the feed hopper 1 and on the sidewhere it is raised it separates them without causing them to gatherlocally, thereby distributing immature green peas in the bottom of thefeed hopper 1 with uniform density. This swing movement is effected fora predetermined time subsequent to the sending of a discharge signalfrom a weighing hopper, so as to prevent immature green peas from beingdamaged or thickly distributed.

The immature green peas thus uniformly distributed in the bottom of thefeed hopper 1 are then placed on the conveyors 5 traveling at a constantspeed in mutually opposite directions, the conveyors being driven for apredetermined time. The immature green peas are fed, in constant amountswith orderly arrangement and uniform density, to the pool hoppers 10through the gates 4 of predetermined cross-section without slippage bythe guide projections 6 on the conveyors 5. That is, they are fed inconstant amounts equal to 1/3-1/7 of the target combination weight fromthe feed hopper to the respective pool hoppers of the automatic weighingmachines. They are then put into the weighing hoppers 12 of theautomatic weighing machines. Subsequently, the pool hoppers 10, whichare now empty, are fed with immature green peas in constant amounts inthe manner described above to be ready for the next delivery to theweighing hoppers. The contents of the weighing hoppers are weighed bythe respective automatic weighing machines and the weight values arecombined in an arithmetic circuit in such a manner as to provide acombination which is equal to or greater than and the nearest to thepreset weight value, and the lids of the weighing hoppers 12 ofautomatic weighing machines corresponding to that combination are openedto discharge the immature green peas.

The discharged immature green peas are collected in the collectinghopper 14 through the collecting chute 13, and then dropped into thecollecting box 16 on the belt conveyor 15 by opening the lid of thecollecting hopper when the collecting box comes just below thecollecting hopper 14. On the other hand, the pool hoppers 10 belongingto the automatic weighing machines 11 which have been selected receivedischarge signals from the weighing hoppers 12 and discharge theirimmature green peas into the weighing hoppers, whereupon the lids of thepool hoppers 10 are closed. Immediately thereafter, the swing plate orplates 9 and conveyors 5 belonging to the pool hoppers 10 are operatedin the manner previously described to feed immature green peas inconstant amounts to the pool hoppers 10; such operation is repeated manytimes so that computations of combinations of weights are continuouslyeffected.

While in the illustrated embodiment, the feeding of immature green peasto the feed hopper 1 has been effected by using the level controlphototubes 3 and the feed conveyor 2 controlled by the latter, it may bemanually effected without using them.

Depending upon the type of objects of weighing, the pool hoppers 10 maybe omitted or may be replaced by shutters which will be installed at thedelivery ends of the conveyors 5 and which are adapted to be opened andclosed in response to discharge signals from the weighing hoppers 12.

Further, while immature green peas selected as a result of computationsof combinations of weights have been collected in the collecting hopper14 through the collecting chute 13 and then received in the collectingbox 16 on the belt conveyor 15, it is also possible to discharge them toa packaging machine directly from the collecting hopper 14.

As many apparently widely different embodiments of this invention may bemade without departing from the spirit and scope thereof, it is to beunderstood that the invention is not limited to the specific embodimentthereof except as defined in the appended claims.

We claim:
 1. A combinatorial weighing system comprising a plurality ofweighing mechanisms each comprising a feed hopper, a swing plateinstalled substantially in the middle of said hopper and adapted toswing in a vertical plane, at least a pair of conveyors extending inmutually opposite directions with their adjoining ends positioned belowsubstantially the middle of the bottom of said feed hopper and withtheir delivery ends positioned outwardly of the lower ends of thelateral walls of said feed hopper, and at least a pair of automaticweighing machines opposed to each other and positioned below thedelivery ends of said conveyors, wherein combinations of the weightvalues of objects weighed by the automatic weighing machines included inthe individual weighing mechanisms are computed to provide a combinationof weight values which is equal or the nearest to a predeterminedweight.
 2. A combinatorial weighing system as set forth in claim 1,wherein said swing plate is adapted to swing through about 45° on eachside of the horizon.
 3. A combinatorial weighing system as set forth inclaim 1, wherein said swing plate is adapted to swing for apredetermined time.
 4. A combinatorial weighing machine as set forth inclaim 1, wherein said conveyors are adapted to travel for apredetermined time.
 5. A combinatorial weighing system as set forth inclaim 1, wherein the transfer surfaces of said conveyors are providedwith guide projections for objects of weighing.
 6. A combinatorialweighing system as set forth in claim 1, wherein in response todischarge signals from the weighing hoppers of automatic weighingmachines selected as a result of computations of combinations ofweights, the vertical swing movement of said swing plate and thetraveling movement of said conveyors are successively effected so as tofeed the objects of weighing to the weighing hoppers of automaticweighing machines selected as a result of said computations ofcombinations.
 7. A combinatorial weighing system comprising a number ofautomatic weighing machines arranged in two opposed rows, a swing plateattached to substantially the middle portions of the lateral walls of afeed hopper for opposed automatic weighing machines and adapted to swingabout 45° on each side of the horizon for a predetermined time, andopposed conveyors which are disposed with their adjoining endspositioned below substantially the middle of the bottom of said feedhopper and with their delivery ends positioned outwardly of the lowerends of the lateral walls of said feed hopper and which are adapted totravel at a constant speed in mutually opposite directions for apredetermined time and are provided on their transfer surfaces withguide projections for objects of weighing, wherein in response todischarge signals from the weighing hoppers of automatic weighingmachines selected as a result of computations of combinations ofweights, the vertical swing movement of said swing plate and thetraveling movement of said conveyors are successively effected so as tofeed the objects to the weighing hoppers of said automatic weighingmachines selected as a result of said computations.